58 



A PRIMEE OF FORESTRY. 



land, whether Hat, hilly, or mountainous, and the char- 

 acter of the surface covering. These are all connected 

 with the temperature in a special manner. Lastly, it 

 is affected by the winds and the moisture of the atmos- 

 phere. Now, it is clear that of all these factors of 

 climate the forest can influence only the wind, the 

 moisture, and the surface covering; but heat (with 





mi 



m 



'^ "^^HHHV^ 



?*JI 



^: ,, , -: .^«r.«:.. :-.:.. ^ .*.-.-..'. 





Fig. 39.— The forest cover. Oregon. 



which the surface covering has so much to do), mois- 

 ture, and wind are the three things which change when 

 we say that the weather changes. These are just the 

 points where a change due to the forest would have 

 most effect on daily life. The influence of the forest 

 is exerted upon them in two wa3^s: 



First. The forest cover intercepts the rain and the 

 rays of the sun, checks the movement of the air, and 

 reduces the radiation of heat at nio-ht. 



